XR650R Needs a rebuild

xrdad

My 2000 XR650R died on the freeway Monday. I walked it home (7 miles) since my truck was in the driveway and none of my buddies would answer their cell phones! Anyways, I pulled the engine out, and tore the top end down, and found a broken timing chain. The rings have an end gap of .052 thousands of an inch. Hmmm... might be the reason the engine's been burning a quart of oil every 700 miles or so! The piston looks perfect, no marks or carbon buildup. It does show some wear on the skirts though. The exhaust valve stems have a fair amount of carbon buildup in the exhaust ports. All bearings, camshaft, and rockers look fine. The bore is perfect, no scratches, nothing. The original crosshatch honing pattern is visible. Have I missed anything?
Based on previous posts, the HRC timing chain setup costs over $500! Is it worth it? What about the Kibblewhite valve set, how expensive are they? Or are the stock replacement parts good enough? I ride the bike to work every day (40 miles round trip) and putt around Prairie City once a month with the kids.

khelton

Thumpmeister

I just rebuilt my 650 this past summer, and heres what I experianced.
Personally, I went with a full oem rebuild. I used OEM valves, piston, etc. I don't want to have to worry about my bike later on down the line, so I went with parts that I knew would last. Honda takes great pride in making their parts, and thats why they cost so much. I also replaced my cam chain as well. Turns out those wear out pretty easily. I just went with the stocker again on that one. I might stick a hotcam stage one in later on down the line, but that would be it.
If you want reliability, and something that you know will last a long time, go with the OEM stuff. Also, when I tore mine apart, the cylinder looked all good, except for the very top. What you describe sounds exactly like what I had. Since you have that much clearance, it sounds like you had some piston slap. I did, and I had to send my cylinder off to milenium technologies. They do top notch work, and for $200, I pretty much got back a brand new cylinder.
And lastly, when you order your parts, I reccommend ordering AT LEAST two of those long head studs that you bolt the head on to. When I was torquing my head down after getting all the parts finally, I managed to torque down 3 studs, then the fourth one snapped, and I said a few words. Turns out those Honda head studs are pretty much only a one time thing. They're easy to replace, though. If one breaks, just take a pair of vice-grips, and twist it out.
If I think of anything else, I'll post it.

ghoti

My 2000 XR650R died on the freeway Monday. I walked it home (7 miles) since my truck was in the driveway and none of my buddies would answer their cell phones! Anyways, I pulled the engine out, and tore the top end down, and found a broken timing chain. The rings have an end gap of .052 thousands of an inch. Hmmm... might be the reason the engine's been burning a quart of oil every 700 miles or so! The piston looks perfect, no marks or carbon buildup. It does show some wear on the skirts though. The exhaust valve stems have a fair amount of carbon buildup in the exhaust ports. All bearings, camshaft, and rockers look fine. The bore is perfect, no scratches, nothing. The original crosshatch honing pattern is visible. Have I missed anything?Based on previous posts, the HRC timing chain setup costs over $500! Is it worth it? What about the Kibblewhite valve set, how expensive are they? Or are the stock replacement parts good enough? I ride the bike to work every day (40 miles round trip) and putt around Prairie City once a month with the kids.

Ted K.

How many miles did she go? Sounds like it still had plenty left if it weren't for the cam chain.

xrdad

The HRC timing chain, sprockets tensioners and guide cost over $500 if purchased separately from Service Honda. None of these parts are interchangeable with the stock ones.
I bought the bike last Feburary, and installed an analog speedometer. Since then, I've ridden it 3600 miles. As for the previous owner... he rode it 99.9% of the time off road... hard, so who knows? The bike looks kinda rough, so maybe 10,000 miles total? And yes, it did have alot of piston slap. When riding on the highway in the #1 (fast) lane, next to the concrete wall, the noise bounced back at me... loudly!
How about the bottom end? How long do the crank and rod bearings last? Is it wise to split the case and check them while it's sitting on the workbench? Or, is there a way to check them while the bottom end is still together?
Hey Thumpmeister, how much did your overhaul cost? I'm leaning towards a stock rebuild with a Hot Cams stage 1 cam.

Shawn_Mc

Does anyone here know if the stock XR650 piston is forged? If it is, I can see using an OEM piston. But if its not, a forged replacement will get you at least three times the life.

Id say the end gap would be due to the piston slap, or rocking of the piston in the bore. Assuming you had the ring square in the bore when you measured it, .052" is a bunch. Was that MM or inch? If it was MM, its pretty close Id think. To have it that far out Id think you'd have to have a significant ridge in the cylinder. Was there a ridge?

xrdad

The stock piston is cast, as are most of the aftermarket units. The end gap is in thousandths of an inch. There is no ridge in the cylinder. I think the large ring end gap is due to ring wear, not cylinder wear.

Shawn_Mc

The stock piston is cast, as are most of the aftermarket units. The end gap is in thousandths of an inch. There is no ridge in the cylinder. I think the large ring end gap is due to ring wear, not cylinder wear.

Ted K.

What does the book spec the end gap at? Id think it'd be .022 to .028?

snaggleXR650

Hey, about the crank bearings. A mostly Euro supermoto site (visordown.com) claims that the big end of the crank goes with extended high RPM riding common with supermoto. Strange, I don't hear about it from the baja riders/racers which also have extended high RPM riding. Just thought I would mention it. I think, for the most part I would tear it all down and do a good once over of the bottom end also. Peace of mind at least, not to mention time saved by fixing it now rather than later after you put it all back together and then have more problems. Do it right the first time... Good luck

Xr650rhonda

It seems like : intake valves, timing chain, and the connecting rod are key areas to be concerned about as far as failure. The next time I rebuild mine, I 'm using the Carrillo connecting rod with it's replaceable bushings.

HC

check your oil filter for metal, that could give a hint on what going on below. if the chain is a weak area ( $500 ! for the assembly , ouch!) , ya gotta think some body would be making a better unit, and forged piston.

ODSC1

I have a 2000 650R that's burning oil. Over the winter I'll replace the rings and piston. If I want to do a complete top end job how much stuff do I replace? Any estimates on cost? For those that have done a complete job did you replace the cam chain sprockets and tensioner when you replaced the chain?

Another option I thought of is to replace the piston and rings, buy a new bike transfer all my goodies to the new bike and sell the old one. It might be cheaper for me in the long run to do this.